1. Field of the Invention
The present invention relates generally to covers for protecting basins from overexposure to sunlight and airborne debris and, more particularly, to a retractable cover unit for hot water basins of a crossflow cooling tower.
2. Discussion of the Prior Art
A crossflow cooling tower typically includes a fill structure comprised of a number of vertically stacked and horizontally staggered splash bars which are arranged beneath a hot water distribution basin so that hot water, e.g. having a temperature of about 100.degree. F., falls through the structure over the splash bars while air is directed in a transverse direction through the structure.
During use of these cooling towers, especially in low to middle latitude locations where the towers are exposed to a significant amount of sunlight and warmth, algae growth within the hot water distribution basins is a problem.
Where algae is a problem, frequent cleaning of the distribution basins is required in order to reduce the adverse effect the algae has on efficient operation of the tower. In addition to frequent cleaning of the basins, it is known to provide a cover comprising a frame constructed immediately over the basins and several rigid sheets of plywood or the like. In use, once the frame is constructed, the plywood is laid on top of the frame in order to prevent sunlight from reaching the basin so that algae growth is inhibited.
Numerous problems arise during use of the conventional cover construction. For example, because large sheets of plywood are used, it is difficult for maintenance personnel to remove the cover in order to gain access to the distribution basins. Further, as sometimes occurs, the water level within the basins rises to a point at which the water lifts the plywood sheets from the frame, allowing the sheets to float out of position from over the basin.
An additional problem raised in using the conventional construction occurs in petrochemical applications where gases may be introduced into the basins along with the hot water to be cooled. These gases become trapped beneath the conventional cover unit, and there is a concern that a potentially hazardous condition would exist if the cover was not provided with some means for allowing such gases to escape.